1. Field
The present invention relates generally to an optical fiber distribution cabinet for use in a passive optical network (PON), and more particularly, to an optical fiber distribution cabinet for interconnecting optical fibers of a feeder cable with optical fibers of one or more distribution cables in the outside plant of a PON.
2. Related Art
For as long as fiber optics has existed, so has fiber management. The most sophisticated networks in the world would be useless if a thin filament of glass could not be properly routed, protected and traced from its origin to its destination. A passive optical network (PON) is a point-to-multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises. The PON architecture has gained worldwide acceptance and now underlies much of the growth of the telecommunications industry.
In applications employing PON technology, the difficulties of fiber management are further complicated by optical splitters and by the challenge of managing unknown take rates. In response to this complexity, a new system for managing outside plant was developed: what is commonly known as a fiber distribution hub (FDH).
Generally, a FDH is a simple box that houses multiple optical splitters, and to which multiple subscribers are routed for connection to those splitters. The FDHs are typically designed to be installed outdoors, but recently they have also been installed indoors for vertical multiple distribution units (MDUs). The FDHs are all passive devices (no power required), and most of them can be installed on a pole, on a pad/pedestal, or on top of a vault.
Most U.S.-based PON systems use a cabinet fiber distribution hub (CFDH) or a pedestal fiber distribution hub (PFDH) along with fiber distribution splitters. Although CFDHs and PFDHs meet Telecommunication (Telco) service provider network requirements, the typical FDHs and fiber distribution hub splitters use proprietary splitters and a fixed internal cabling methodology leading to difficulty in service. These FDH splitters typically have input and output pigtails. Due to variation in FDH configuration size and configuration, it is often necessary for a Telco service provider to stock FDH splitters optimized for a specific FDH model. Also, although a fiber distribution splitter may have one package size, there are multiple cabinet fiber distribution hubs and pedestal fiber distribution hubs specific variants with differing pigtail lengths for efficient fiber routing.
With a PFDH currently available in the market, another problem often arises because the connectors in the input and output distribution field are secured behind an interior bulkhead and are more difficult to clean and inspect connectors installed behind input and output distribution fields. In addition, in some of current CFDH or PFDH designs that use F1 and F2, a separate jumper is needed to connect the feeder and distribution cables.
In servicing the FDHs, field technicians frequently need to conduct maintenance or reassign copper or fiber optic circuits in outside plant cabinets. It is desirable that these cabinets have a design feature that holds the cabinet door in an open (maintenance) position or have a design feature that allows these doors to be easily removed and reinstalled to allow the field technician free access to the cabinet interior without interference from the door. There are three common methods to secure a cabinet door in a maintenance position.
First, there is a sliding bar latch with fixed slots to hold the cabinet door in various pre-assigned positions. This approach effectively holds a door in fixed positions but requires a fixed volume within the cabinet. As a practical matter, this design approach is not suitable for small cabinets due to the comparatively large percentage of cabinet interior volume required to implement.
Second, there is a use of removable door. With this method, the cabinet door can be easily removed and re-installable. This design approach is feasible in applications where the field technician is operating at ground level and no functional components are stored on the cabinet door.
Third, a removably attachable tether is used to hold the door open. To use this approach, the field technician must be able to secure the tether to the back of the cabinet or a nearby fixed structure.
Therefore, there is a need for providing external FTTP PON hubs which provide an easy way to configure for different combinations of feeder fiber cables and distribution fiber cables, an easy way to connect service to customers, and means for pass-through connections. Additionally, there is a need for an easy way to route feeder and distribution cables to the ports in the bottom of the external hub. There is also a need for cost-effective way to secure a cabinet door utilizing a minimal cabinet space. The present invention has been made with the forgoing situations taken into consideration.